Mind you to use docker checkpoint you have to turn on experimental docker And probably install CRIU https://archlinux.org/packages/extra/x86_64/criu/
The script is:
sudo docker compose up -d
sudo docker checkpoint create --leave-running=false unrar_container check1
sudo docker start --checkpoint check1 unrar_container
(a very hacky attempt by serizon & hnkm , the readme is hastily written by serizon.)